Change speed gear



-March 21, 1939. G. MEYER CHANGE SPEED GEAR Filed May 6, 1936 2 Sheets-Sheet 1 March 21, 1939. MEYER 1 2,151,132

CHANGE SPEED GEAR Filed May 6, 1936 2 Sheets-Sheet 2 Fig. .3.

Inventor: W W

Patented Mar. 21, 1939 PATENT OFFICE CHANGE SPEED GEAR Gustav Meyer, Friedrichshafen-on-the-Bodensee, Germany, assignor to Maybach-Motorenbau Gesellschaft mit beschrankter Haftung, l riedrichshafen-on-tlie-Bodensee, Germany, a corporation of Germany Application May 6, 1936, Serial No. 78,243

Germany May 16, 1935 14 Claims.

In the known change speed gears of the kind comprising a train of mainshaft parts and a train of layshaft parts, dog clutches for coupling together the parts of the said trains,- and a number of pairs of obliquely toothed gear wheels in constant mesh, one wheel of each pair being mounted on one of the mainshaft parts and the other on one of the layshaft parts, considerable difliculties arise with regard to taking up the axial thrusts of the gear wheels which are mounted on the intermediate parts of the shaft trains. Since in the interests of reducing manufacturing cost .and overall length, and therefore weight of the gearbox, it is not desirable to provide thrust bearings on each side of each of the intermediate gear wheels, it follows that the thrusts from these gear wheels must be transmitted through the intermediate parts of the shaft trains to thrust-absorbing bearings provided at the ends of the said trains. Roller bearings are generally employed between the various parts of the shaft trains, and if these bearings are subjected, while they are running, to the heavy axial thrusts which originate from the gear wheels, rapid wear occurs,

leading after a certain time of running, to inuries to the bearings, unsteady running of the gear and even to fracture of shaft elements and other parts.

According to the invention, the aforesaid difflculties are obviated in a simple way by the direction of the obliquity of the teeth of the gear wheels mounted on intermediate parts of the shaft trains, and by the construction of the bearmgs provided between the parts of the shaft trains being such that the axial thrusts produced by the transmission of the power of the driving engine are transmitted by bearings between shaft parts which do not make any relative movement with respect to each other while the thrust is acting on them.

Two change speed gears constructed according to the principles of the invention are shown in the accompanying drawings.

Figure 1 shows the first of these change-speed gears in part axial section and part elevation.

Figure 2 shows diagrammatically in cross section the arrangement of the reverse speed gear wheels of the change speed gear shown in Figure Figure 3 shows the other change speed gear in part axial section and part elevation.

The change speed gear shown in Figure 1 comprises a mainshaft train of four parts, namely the driving shaft I, the shaft 5', the hub portion of the gearwheel 9, and the driven shaft l3.

It should be particularly noted that although the hub portion of the gear wheel 9 is hollow and very short, it is functionally one of the parts of the mainshaft train and is so regarded in the following description and in the appended 5 claims. Similarly the layshaft train is considered -to be comprised of three parts-the short shaft of the gear wheel 22, the shaft l6, and the shaft 26.

Mounted on the driving shaft l is a gear wheel 10 2 which has oblique teeth and is supported at both sides by ball bearings and on one side is provided with dogs 3 for a dog clutch 4 slidably mounted on the shaft element 5. In a recess formed in the end of the driving shaft 15 l, the shaft element 5 is mounted in a roller bearing 6. On the other end of the shaft element 5 there is likewise a dog clutch 1 adapted to be brought into engagement with dogs 8 formed on the hub of the gear wheel 9. This 20 end of the shaft element 5 also carries a roller hearing I 0 by means whereof the said shaft element is mounted in a recess in the hub of the gear wheel 9. Between the two dog clutches 4 and I is a gear wheel I l with oblique-teeth, the 25 angle of the oblique teeth being directed so as to be contrary to the direction of rotation (seen from the driving side); in this case, the teeth of the gear wheel II are left-hand helices for right-hand (clockwise) rotation of the shaft I. 30

In the hub of the gear wheel 9, the shaft element I 3 is also mounted in a roller bearing l2, and mounted on the said shaft element [3 is a slidable gear wheel l4 carrying a dog clutch IS. The power of the driving engine is trans- 35 mitted through the shaft element I3, to the driving shaft 30 leading to the driven wheels of the vehicle.

The obliquely toothed gearwheel 22 of the layshaft train is in constant mesh with the gear 40 wheel 2 of the mainshaft train and is mounted on both sides in ball bearings. The hub of this gear wheel has a recess into which projects one end of the shaft IS, a roller bearing 20 being provided between the two parts. The other end 45 of the shaft l6 projects similarly into a recess provided in the end of the shaft 26, with the interposition of a roller bearing 2|. The shaft l6 furthermore carries a gear wheel I! constantly in mesh with the gear wheel II and slidable 50 dog clutches l8 and I9 adapted to engage dogs 24 and 25 respectively provided on the hub of the gear wheel 22 and on the end of the shaft 26. The shaft 28 also carries an obliquely toothed gear wheel 23 constantly in mesh with the gear 55 wheel 9 and two gear wheels 21 and 28 with straight spur teeth.

All the roller bearings 6, I0, I2, 20, 2I are so constructed that there is only one shoulder 32 in the recess in which the rollers run, the shoulders being arranged so that the bearings are capable of transmitting axial thrusts corresponding to compression of the shaft 'part 5 or I6 or of the hub of the gear wheel 9 but not thrusts in the reverse direction. In the event of slight displacements resulting from axial thrusts, the shaft element can thus bear in the direction of the efiective thrust in the corresponding bearing withoutv the production of stress on a shoulder in the bearing'mounted on the other end of the shaft element.

Such a gear operates as follows:

In the first speed, the power is transmitted from the shaft I through the gear wheel 2,'gear the gear wheel 22. The dog clutch I8-24 is engaged, so the bearing parts of 20 do not make any relative movement. The roller bearing I0 is also stationary, due to the engaged dog clutch -'|-8, and transmits to the shoulder of the hub race of the gear wheel 9 the axial thrust which is directed from the gear wheel II towards the bearing I0.

In the fifth speed, the dog clutches 3-4 and 1-8 and I5 arev engaged. Without the parts of the roller bearings 6, I0, I2 making any relative rotary movements, the power is transmitted directly from the shaft I through the clutches 3-4, 'I.-8 and I5 to the driven shaft 30, no appreciable axial pressures being produced since power .is not transmitted by any of the gear wheels.

The following table shows the running condition of the bearings for the difierent speeds.

Running condition of the bearings of the shaft elemcntafi and 16 for the different speeds Bearing 6 20 21 10 Speed:

I Runs (withoutpressure). Stationary Stationary Runs (without pressure). II Runs (without pressure). Stationary Stationary Runs (without pressure). 111 stafiiolggy (with axial Runs(withoutpressure). Stationary (with pres- Runs (withoutpressure).

I sure 1,.1 r. 1V Runs (withoutpressure)- Stationary (with .pres- Runs(wi?houtpressu ;e) Stationary (with pressure is tarpon. we: lrg'a sure). V.. Stationary (without Runs (withoutpressure). Buns(w1thout pressure). Stationary (with out pressure). pressure).

wheel 22, clutch 24-I8, shaft element I6, clutch IS-25, shaft element 26, gear wheels 28, I4 to are taken up by the bearings provided for these wheels directly in the casing. Since in the first and second speeds, no power is transmitted by the gear wheels II and Il, these latter also do not give rise to any appreciable axial thrusts.

-When the third speed is engaged, the power is transmitted from the shaft I through -the dog clutch 3-4 to the shaft element 5 and thence through the gear wheels II and I1 to the shaft element I6 and through the clutch I9-25 and the gear wheels 23, 9, clutch I5 and the shaft element I3 to the driven shaft 30. Due to the obliquities of the teeth of the gear wheels II and I1 an.axial thrust acts towards and upon the roller bearing 6 of the shaft element 5 and the roller bearing 2| of the shaft element I6. Since the clutch 3-4 is engaged, however, the roller bearing 5 is stationary relatively to the gear wheel 2 or the shaft element 5. The rollers, of the bearing 5 therefore transmit this thrust without rotating relatively to the bearing races. The same applies to the roller bearing 2|. Due to the engagement of the-clutch I0-25, this 'latter bearing also is stationary relatively to the After cutting off the engine fuel supply, that I is to say, when the gear is being driven by the vehicle wheels, the direction of the axial thrust for the various speeds is the converse of that described hereinbefore. In this case,-the axial thrust is taken partly by bearings which are in motion. Since, however, the power transmitted in this case is substantially lower, the wear on the bearings concerned is only slight. The gear wheel 21 .is for the reverse speed which is obtained in known manner by means of an intermediate gear wheel 3| (shown in chain lines in the drawings) between the two gear wheels 21 and- Id.

In the change speed gear shown in Figure 3 the mainshaft train is composed of the shaft IOI, hub of the gear wheel BI, shaft I03, and shaft I05, and-the layshaft train is composed of the shaft I02, hub of the gear wheel 51, and

shaft I04, I08.

The shaft IN is an extension of the shaft 5| to which the power of the engine is applied and is carried at one end in a thrust-absorbing bearing 05 and at the other bearing 55 running in a recess in the hub of the gear. wheel 5|. One end of the shaft I03 is similarly carried in.a roller bearing'60 running in' a recess in the hub of the gear wheel 5|, and the other end is provided with a recess in which runs a. roller bearing I05 supporting.

'one end of the shaft I05. The other end of the shaft I05 is carried in a thrust-absorbing bearing I01.

Of thelayshaft train the shaft I02 is carried at one end in a thrust-absorbing bearing 06 and at the other end in a roller bearing 10 running in a recess in the hub of the gear wheel 51. One end of the shaft I04, I08 is similarly carried in a roller bearing II running in a-recess in the hub of the gear wheel 61, and the other end is carried in a thrust-absorbing bearing I00. The roller bearings 50, 50, I05, 10 and 'II are formed, like the corresponding bearings in Figend in a roller ure 1, with onlyone shoulder on their recesses,

mainshaft and layshaft trains.

Obliquely toothed gear wheels 52 and 59 are mounted on the parts IN and I03 of the mainshaft train and are in constant mesh with gear wheels 12 and 13-mounted on the parts I02 and I04 .of the layshaft train. The'gear wheels 6| and 61 also have oblique teeth and are in constant mesh with one another. A straight toothed spur wheel 64 is mounted on the shaft I06 and has do'gs adapted to engage with one 15 of the sets of dogs provided onthe dog clutch 65. On the layshaft part I08 there is also mounted a sliding spur wheel 18 adapted to be brought into mesh with the gearwheel 64. 'The radial forces of the gear wheels 6|, 61, 59 and 13 are 20 taken by roller bearings 9|, 92, 93, 94, 91 and 98 mounted in the casing.

The directions of the teeth of the gear wheels 6| 61, 59 and 13 are chosen in accordance with the principle explained in connection with Figure 1. That is to say, for clockwise rotation of the driving shaft I the teeth of the wheels 6| and 59 are'left hand helices, and the teeth of therwheels 61 and 13 are (necessarily) right hand helices. It then follows that when the wheels are rotating in their normal directions and one of the mainshaft wheels (6| or 59) is the driving wheel of its pair its thrust is transmitted from the shaft element on which it is mounted only to the adjacent shaft element which is nearer the end of the change speed gear intended to receive the normal driving torque. Conversely the transmission of the thrusts of the driven wheels is in the opposite direction. 'These directions in each case pro- 40 vide for the transmission of the thrust through the roller bearings which .are stationary.

At the first speed the torque is transmitted from the shaft 5| through the gear wheels 52 and 12, the clutch 68, gear wheel 61, gear wheel 5 6|, clutch 51, gear wheel 59, gear wheel 13, gear wheel 18 and gear wheel-64, the right end clutch of the sleeve25, and the shaft element I06 to the driven shaft 80.

With the second speed engaged the transmissiqn of power takes place from the shaft 5| through the gear-wheels 52 and 12, clutch 68, gear wheel 61, clutch 69, gear wheel 16, gear wheel 64, the right end clutch of the sleeve 65, and the shaft element I06 to the driven shaft 1m; third speed; shaft 5| through gear wheels 52 and 12, clutch 68. gear wheel 61, gear wheel 6|, clutch 51, clutches 65 to shaft fourth clutch 68, gear wheel 61, clutch 69, gear wheel w 13,v gear wheel 59, clutch to shaft 80; fifth 65 54, gear wheel 6|, gear wheel 61, clutch 69, gear wheel 13, gear wheel 59, clutch 65 to the driven shaft 80.

With the third speed engaged, whereby the clutch 68 is engaged at the gear wheel 61 and the clutch 51 at the gear wheel 6| and the clutch 65 at the gear wheel 59, the axial thrust of the gear wheel 61 is transmitted by the bearing "to the shaft element I02 and by the body of the gear wheel 12 to the end bearing 96.

The axial thrust of the gear wheel 6| is transmitted by the bearing 60 on the shaft element I03 and by the body of the gear wheel 59 through the bearing I05 on the shaft element I06 from where it is transmitted to the end bearing I01. There is no relative movement of the rollers of bearings 10, 60 and I05 vis-a-vis their bearing surfaces since the clutches 68, 51 and 65 do not allow any relative rotary movement of the said bearings.

The gear wheels 64 and 18 are spur wheels. The gear wheel 64 can be brought into connection with the shaft element I06 by means of twin clutch 65. The gear wheel 18 can be disengaged from the gear wheel 64 thereby obtaining the reversespeed by means of an intermediate wheel of the known type, in the same way as shown on Fig. 2 for the gear of Fig. 1,

for instance by transmitting the torque from shaft 5| through the gear wheels 52 and 12, the shaft element I02, the clutch 68, the gear wheels 61 and 6|, the clutch 51, the shaft element I03, the gear wheels 59 and 13, the shaft element I08, the wheel 18, an intermediate gear wheel 3| (Fig. 2), the gear'wheel 64, the right I end clutch of the sleeve 65, and the shaft element I06 on the shaft 80.

I claim:

' 1. In a change speed gear? a mainshaft train of more than two parts, a layshaft train, roller bearings between the parts of said trains, said bearings being capable of transmitting axial thrusts corresponding to compression of the train parts, but not thrusts in the reverse direction, a thrust-absorbing bearing at each end of each train, dog clutches for coupling together the parts of said trains, and a pair of obliquely toothed gear wheels in constant mesh, one of said wheels being mounted on an intermediate part of the mainshaft train and the other in the layshaft train, the teeth of said gear wheels being so directed that when the wheels are rotating in their normal directions and the mainshaft wheel is the driving wheel the thrust of the said 'wheel is directed towards the end of the mainshaft train intended to receive the normal driving torque.

2. In a change speed gear of thekind comprising a train of shaft parts, dog clutches for coupling together the parts of said train, and a number of pairs of obliquely toothed gear wheels in constant mesh, one wheel of each, pair being" mounted on one of said train parts: two adjacent, train parts having an antifriction bearing between them which is capable of transmitting axial thrust in one direction only, and an obliquely toothed wheel mounted on one of said adjacent train parts and having the direction of itsteeth-such that when the clutch between the said adjacent train parts'is engaged, and power is being transmitted through the change speed gear in the normal direction, any axial thrust from thesaid wheel acts upon the train part on which the wheel is mounted in the same direction as that in which the said bearing is capable of transmitting thrust from the train part on which the wheel is mounted to the adjacent train part.

3. In a change speed gear of the kind comprising a train of mainshaft parts, dog clutches for coupling together the parts of said train, and a number of pairs of obliquely toothed gear wheels lnconstant mean, one wheel of each pair being mounted on one of said mainshaft-train parts} two adjacent mainshaft-train parts having an antifriction bearing between them which 75 4 is capable of transmitting axial thrust in one direction only, and an obliquely toothed wheel mounted on one of said adjacent mainshafttrain parts and having the direction of its teeth such that when the clutch between the said adjacent train parts is engaged, and power is being transmitted through the change speed gear in the normal direction, any axial thrust from the said wheel acts upon the train part on which the wheel is mounted in the same direction as that in which the said bearing is capable of transmitting thrust from the train part on which the wheel is mounted to the adjacent train part.

4. In a change speed gear of the kind comprising a train of layshaft parts, dog clutches for coupling together the parts of said train, and a number of pairs of obliquely toothed gear wheels in constant mesh, one wheel of each pair being mounted on one of said layshaft-train parts; two adjacent layshaft-train parts havin an antifriction bearing between them which is capable of transmitting axial thrust in one direction only, and an obliquely toothed wheel mounted on one of said adjacent layshaft-train parts and having the direction of its teeth such that when the clutch between the said adjacent train parts is engaged, and power is being transmitted through the change speed gear in the normal direction, any axial thrust from the said wheel acts upon the train part on which the wheel is mounted in the same direction as that in which the said bearing is capable of transmitting thrust from the train part on which the wheel is mounted to the adjacent train part.

5. In a change speed gear, an intermediate shaft part the ends of which project into recesses formed in the adjacent shaft parts, antifriction bearings between said shaft parts capable of transmitting axial thrusts in one direction only,

dog clutches for coupling together said shaft parts, and a pair of obliquely toothed gear wheels in constant mesh, one of said wheels being mounted on said intermediate shaft part, the teeth of said gear wheels being so directed that when two of said shaft parts are coupled by the engagement of the dog clutch between them and power is being transmitted through the change speed gear in the normal direction, any axial thrust from I the gear wheel mounted on said intermediate shaft part acts in the same direction as that in which the antifriction bearing between the coupled shaft parts is capable of transmitting thrust from said intermediate shaft part to the adjacent shaft part.

6. In a change speed gear, an intermediate shaft part recessed to receive the ends of the adjacent shaft parts, antifriction bearings between said shaft parts capable of transmitting axial thrust in one direction only, dog clutches for coupling together said shaft parts, and a pair of obliquely toothed gear wheels in constant mesh, one of said wheels being mounted on said intermediate shaft part the teeth of said gear wheels being so directed that when two of said shaft parts arecoupled by the engagement of the dog clutch between them and power is being transmitted through the change speed gear in the normal direction, any axial thrust from the gear wheel mounted on said intermedia'teshaft part acts in the same direction as that in which the antifriction bearing between the coupled shaft parts is capable of transmitting thrust from said intetrmediate shaft part to the adjacent shaft par "'7. Ina change speed gear, an intermediate shaft part recessed at one end to receive the end of one of the adjacent shaft parts and projecting at its other end into a recess in the other adjacent shaft part, antifriction bearings between said shaft parts capable of transmitting axial thrusts in one direction only, dog clutches for coupling together said shaft parts, and a pair of obliquely toothed gear wheels in constant mesh, one of said wheels being mounted on said intermediate shaft part, the teeth of said gear wheels being so directed that when two of said shaft parts are coupled by the engagement of the dog clutch between them and power is being transmitted through the change speed gear in the normal.

direction, any axial thrust from the gear wheel mounted on said intermediate shaft part acts in the same direction as that in which the antifriction bearing between the coupled shaft parts is capable of transmiting thrust from said intermediate shaft part to the adjacent shaft part.

8. In a change speed gear, a mainshaft train of more than two parts, a layshaft train, antifriction bearings between the parts of said trains capable of transmitting axial thrusts in one direction only, a thrust absorbing bearing at each end of each train, dog clutches for coupling together the parts of said trains, and a pair of obliquely toothed gear wheels in constant mesh, one of said wheels being mounted on an intermediate part of the mainshaft train and the other in the layshaft train, the teeth of said gear wheels being so' directed in relation to the thrust transmitting directions of said antifriction bearings that when said intermediate mainshaft part is coupled .to one of the adjacent mainshaft parts by the engagement of the dog clutch between them and power is being transmitted through the change speed gear in the normal direction, any axial thrust from the gear wheel mounted on said intermediate mainshaft part acts in the same direction as that in which the antifriction bearing between the coupled shaft parts is capable of transmitting thrust from said intermediate mainshaft part to the adjacent mainshaft part.

- 9. In a change speed gear, a layshaft train of more than two parts, a mainshaft train, antifriction bearings between the parts of said-trains capable of transmitting axial thrusts in one direction only, a thrust absorbing hearing at each them and power is being transmitted through the change speed gear in the normal direction, any axial thrust from the gear wheel mounted on said intermediate layshaft part acts in the same direction as that in which the antifriction bearing between the coupled shaft parts is capable of transmitting thrust from said intermediate layshaft part to the adjacent layshaft part.

10. In a change speed gear, a mainshaft train of more than two parts, a layshaft train, antifriction bearings between the parts of said trains capable of transmitting axial thrusts in one direction only, a thrust absorbing bearing at each end of each train, dog clutches for coupling together the parts of said trains, and a pair of obliquely toothed gear. wheels in constant mesh, one of said part of .1

wheels being mounted on an intermediate the mainshaft train and the other on an intermediate part of the iayshaft train, the teeth of said gear wheels being so directed in relation to the thrust transmitting directions of said antithrust from the gear wheels mounted on said intermediateshaft parts acts on the shaft part carrying the respective gear wheel in the same direction as that in which'the antifriction bearing between said last-mentioned shaft part and the adjacent shaft part coupled to it is capable of transmitting thrust from the intermediate shaft part to the adjacent shaft part.

11. In a change speed gear, a pair of obliquely toothed gear wheels in constant mesh, one of said wheels being rigidly mounted on a shaft part journalled at one end in an antifriction bearing carried by an adjacent shaft part and capable of transmitting, axial thrusts in one direction only, andja dog clutch for coupling together said shaft parts, the teeth of said gear wheels being so directed that when said shaft parts are so coupled and power is being transmitted through the change-speed gear in the normal direction,-any

- axial thrustfrom the gear wheel mounted on the shaft part which is journalled at one end in said antifriction bearing acts in the same direction as that in which said antifriction bearing is capable of transmitting thrust to said adjacent shaft part.

12. In' a change-speed gear, a pair of obliquely toothed gear wheels in constant mesh, one of said wheels being rigidly mounted on a shaft part carrying an antifrictlon bearing capable of transmitting axial thrusts in one direction only, an adjacent shaft part journalled at one end in saidantifriction bearing, and a dog clutch for coupling together said shaft parts, the teeth of said gear wheels being so directed that when said shaft parts are so coupled and power is being transmitted through the change-speed gear in the nor--' mal direction, any axial thrust from the gear wheel mounted on the shaft part carrying said antifriction bearing acts in the same direction as that in which said antifriction bearing is capable of transmitting thrust to said adjacent shaft part.

13. In a changespeed gear, a pair of obliquely toothed gear wheels in constant mesh, one of-said' wheels being rigidly mounted on a shaft part journalied at one end in an antifriction bearing carried by an adiacent shaft part and capable of transmitting axial thrusts in one direction only and also joumalled in a bearing mounted directly in the casing, and adog clutch for coupling together said shaft parts, the teeth of said gear wheels being so directed that when said shaft parts are so coupled and power is being transmitted through the change-speed gear in the normal (ii-- rection, any axial thrust from the gear wheel mounted-on the shaft part which is journalled at 1 one end in said antifriction bearing acts in the same direction as that in which said antifriction bearing is capable of transmitting thrust to: said adjacent shaft part.

14. In a change-speed gear, a pair of obliquely toothed gear wheels 'in constant mesh, one of said wheels being rigidly mounted on a shaft part journalled in bearings mounted directly in the casing and carrying an antifriction bearing capable of transmitting axial thrusts in one direction only,

an adjacent shaft part journalled at one end in said antifriction bearing, and a ,dog clutch for coupling together said shaft parts, the teeth of said gear wheels being so directed that when said shaft parts are so coupled and power is being transmitted through the change speed gear in the normal direction, any axial thrust from the gear wheel mounted on the shaft part carrying said antifriction bearing acts in the same direction as that in which said antifriction bearing is capable of transmitting thrust to said adjacent shaft part.

GUSTAV MEYER. 

